Method of continuous spinning of fiber strands into yarns in a spinning chamber



J. METHOD OF CONTINUOUS SPINNING OF FIBER STRANDS INTO RIPKA ETAL.

Sept. 3, 1968 YARNS IN A SPINNING CHAMBER Filed Sept. 6, 1966 2 Sheets-Sheet 1 INVEN ORS fiw J" 7 #144.

Sept. 3, 1968 J. RIPKA ETAL 3,399,523

METHOD OF CONTINUOUS SPINNING OF" FIBER STRANDS INTO YARNS IN A SPINNING CHAMBER Filed Sept. 6, 1966 2 Sheets-Sheet 2 IyI/I 5 J I 55L S X 0 l f INVENTORY ZZZ/1% ATTORNE Y United States Patent METHOD OF CONTINUOUS SPINNING OF FIBER STRANDS INTO YARNS IN A SPINNING CHAMBER Josef Ripka, Usti nad Orlici, and Josef Hybl, Ceska Trebova, Czechoslovakia, assignors to Vyzkumny ustav bavlnarsky, Usti nad Orlici, Czechoslovakia Filed Sept. 6, 1966, Ser. No. 577,256 Claims priority, application Czechoslovakia, Sept. 11, 1965, 5,607/65 2 Claims. (Cl. 57-156) ABSTRACT OF THE DISCLOSURE A method of spinning yarn from a strand of fibers in a spinning chamber in which the fiber strand deposited on the collecting surface of the spinning chamber is twisted in a yarn which is withdrawn from the collecting surface in a plane normal to the axis of the spinning chamber and passing through the axis of the strand so that the strand is twisted symmetrically with respect to its axis, and in which the spinning chamber is rotated about the axis at a speed correlated with the withdrawing speed of the yarn in such a manner that the point of withdrawal of the yarn from the collecting surface of the spinning chamber moves relative to the collecting surface in direction of rotation of the spinning chamber.

The present invention relates to a method of continuous spinning of fiber strands into yarns in a spinning chamber.

In known spinning devices in which a strand of fibers deposited on a rotatable cylindrical collecting surface of a spinning chamber is spun into a yarn by twisting the strand of fibers while withdrawing the yarn from the collecting surface, an important technological parameter, such as the stress in the yarn at the point at which the fibers are twisted together, is neglected.

In contradiction to classic methods of spinning wherein the roving is twisted while being held in the nip between a pair of drafting rollers, most of the new spinning devices operate under reduced control of the fibers at the particular point mentioned above.

Various spinning apparatus using a rotating spinning chamber are known in the art which are constructed with the aim in mind to improve the control of the fibers especially at the point at which they are twisted. To this type of apparatus belongs for instance a device wherein the fiber collecting surface is provided with needles which, however, excessively increase the stress in the yarn at the point of its formation, due to the resistance which the needles offer to lifting or withdrawing the yarn being twisted from the collecting surface. Due to the lifting of these fibers off the needles a great irregularity of the spinning tension is also produced in this apparatus.

A device is also known which has apertures in its collecting surface through which an air flow is produced by underpressure so that the fibers are held by suction on the collecting surface which also increases the stress in the yarn at the point of its formation. Moreover, due to the alternation of solid areas with openings, a pulsating tension is created at the point of yarn formation.

Devices are also known which have no apertures in their collecting surfaces, but which are provdeid with a drawing off surface which insures withdrawing of the yarn from the collecting surface at an angle of (l to 45 with respect to the axis of rotation of the spinning chamber. Thus a slow change of the curvature of the yarn curve adjacent to the collecting surface is determined by the angle of the drawing off surface, which change in ice turn is closely related to a high share of tension within the twisting zone of the total spinning tension at the discharge from the spinning chamber.

Another spinning device has been proposed wherein the collecting surface has no bores and wherein the yarn is withdrawn in a plane substantially normal to the axis of rotation of the spinning chamber, in which the withdrawal plane is, however, displaced in direction of the axis of rotation with respect to the axis of the fiber strand. The disadvantage of this arrangement is an asymmetric twisting of the fibers and an unstable form of the yarn curve which has a bearing upon the high amplitude of stress variations at the twisting point of the fiber strand, besides this arrangement involves a harmful violent change in the direction of the fibers, exceeding In summing up it may be said that the devices and methods discussed hereinbefore operate under unfavorable conditions in the area of yarn formation, judged from the standpoint of twist transmission as well as from the coherence of the staple material being twisted, which in turn necessarily detrimentally affects both the production and the breakage rate in the existing devices. Due to these facts not one of the mentioned devices has so far been employed on an industrial scale.

It is an object of the present invention to provide for a method in which the disadvantages of the known methods of spinning fibers into a yarn in a spinning chamber are avoided.

It is a further object of the present invention to provide for a method in which the stress at the point of formation of the yarn is reduced so as to reduce the breakage rate of the yarn during the spinning thereof from the strand of fibers.

With these objects in view, the method of spinning yarn from a strand of fibers in a spinning chamber rotatable about an axis and having a smooth collecting surface constituted by a surface of revolution having an axis coinciding with the axis of rotation of the spinning chamber, mainly comprises the steps of twisting a fiber strand deposited on the collecting surface into a yarn and withdrawing the yarn from the collecting surface substantially in a plane normal to the spinning axis and passing through the axis of the strand so that the fiber strand is twisted symmetrically with respect to its own axis, and rotating the spinning chamber about its axis and simultaneously withdrawing the yarn from the collecting surface at correlated speeds so as to maintain the sense of the angular velocity of the relative displacement of the point of withdrawal of the yarn from the collecting surface relative to the surface coincident with the sense of angular velocity of the spinning chamber.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatical section through the spinning chamber taken along a plane normal to the axis of rotation of the latter;

FIG. 2 is a partial axial section through the spinning chamber;

FIG. 3 shows a plurality of curves plotted on polar coordinates for different relationship between the relative and the absolute velocity at the point of withdrawal of the yarn from the collecting surface of the spinning chamber; and

FIG. 4 shows a plurality of curves of axial stress development in the yarn corresponding to the curves shown in FIG. 3.

Referring now to the drawing, and more specifically to FIG. 1 of the same, it will be seen that the spinning chamber has a collecting surface 2 on which a strand 3 of fibers is deposited by means known in the art and not forming part of the present invention. This strand of fibers is withdrawn from the collecting surface 2 at Withdrawal point 4 and twisted in a yarn drawn off through the discharge opening 6. In FIG. 1 there are also indicated various velocities and stresses on which the process of the present invention depends, that is:

Wk indicates the sense of angular velocity of the spinning chamber 1;

w indicates the sense of relative angular velocity of the withdrawal point 4;

Vector v indicates the absolute velocity of the withdrawal point 4 in the direction of the tangent 7 at the withdrawal point;

Vector v indicates the relative velocity of the withdrawal point 4 also in the direction of the tangent line 7;

Vector S indicates the axial stress in the yarn at the withdrawal point 4; and

Vector S indicates the axial stress in the yarn at the discharge opening 6.

As can be seen from FIG. 2, the yarn 5 is withdrawn from the collecting surface 2 of the spinning axis on the upper surface of a stationary guide member 11, which upper surface is located in a plane normal to the axis 10 of the rotating spinning chamber 1 and at such elevations so that the yarn is withdrawn in a plane 9 passing through the axis 8 of the strand of fibers 3. In this way the strand 3 is twisted symmetrically with regard to its own axis 8. In FIG. 2 there are also indicated the following stresses and moments:

Vector S indicates the axial stress in yarn 5 at the discharge opening 6 in front of the edge 12 of the opening 6;

Vector S indicates the discharge spinning stress in yarn 5;

Arrow Mk indicates the twisting moment supplied by yarn 5 to twist the strand 3; and

Arrow Mk indicates the resistance twisting moment oifered by the fiber strand 3 to the twisting thereof.

Yarn spinning with the aid of a spinning chamber having a smooth collecting surface 2 constituted by a surface of revolution having a generatrix in form of a curve, the concave side of which faces the axis of rotation of the spinning chamber, is carried out at reduced control of fibers, that is, the fibers are in this case not held in the nip of a pair of drawing rolls, but the fibers are held against the collecting surface only by a centrifugal action. In this case it has been found most advantageous if the twisting of the fiber strand 3 is performed symmetrically with respect to the axis 8 thereof, since in this case, the effect of the twisting moment Mk is also symmetrically distributed through all fibers being twisted and is best utilized for surmounting the resistance moment :M offered by the fiber strand 3.

One of the features which influences the proper spinning of the fiber strand is the discharge spinning stress S in the yarn, on which depends, to a certain degree, the thrust at which the fibers of the spun yarn are pressed against each other in a direction normal to the longitudinal direction of the yarn. However, it has been found that the spinning process proper and thus the formation of yarn are more influenced by the stress S existing at the point at which the fiber strand 3 is being twisted and simultaneously withdrawn from the collecting surface 2.

The value of this stress at the aforementioned point determines the magnitude of the moment M and it is also known that the resistance moment increases as the axial stress increases.

An unfavorable effect on the spinning process is produced by the irregularity of the mass of the fiber strand 3 which is twisted, which influences mainly the variations 4 of both the stress S in the yarn and the moment M of the fiber strand 3.

At a given spinning tension the stress S at withdrawal point 4 depends on the form of the yarn curve in the spinning chamber along the upper surface of the member 11. Theoretically it was established that the shape of this curve with this method of spinning can be approximately expressed by an equation by means of polar coordinates z, x, whereby z for a point M on this curve is the included angle between the tangent 0 on the yarn curve 5 at the point 6 (FIG. 1) which tangent coincides with the vector of axial stress S at the point 6, and a line 1' connecting the point M with the point 6, whereas x is the relative magnitude of the radius vector 1' at the point M with respect to the radius R of the collecting surface 2 (x=r/R), which equation can be written as follows:

In this equation y=ratio of the relative velocity y of the withdrawal point 4 to the absolute velocity v thereof ln natural logarithm; and )(x) =function of x, having a hyperbolic character, for

instance wherein a, b, c, d, are constants.

During carrying out an actual spinning process it was experimentally established that the yarn 5 curves on the upper surface of the member 11 between the withdrawal point 4 and the discharge opening 6 along a curve which is substantially a logarithmic curve. However, the shape of the curve varies within certain limits so that it is necessary to modify the above equation for the curve shape by a variable coefiicient k(t) depending on time, in which case it is possible to express the curve as follows:

By the choice of a proper coefiicient y it is possible, as will be further explained later on, to vary the magnitude of the stress S at the point of yarn formation.

The advantage of the method of the present invention is that by choosing a suitable y, the stress at the point of yarn formation is kept, in dependence upon the discharge stress S within permissible limits, that is under the breaking point of the fiber strand at this point and the effects of detrimental influences as discussed hereinbefore are thereby substantially reduced. This results in a reduction in the breaking rate and therefore the continuity of the spinning process is enhanced.

Between the values of tensions S and S (FIG. 2) the following relation exists:

SVZSC ra In this equation e=base of natural logarithm;

f coefiicient of friction between the yarn and the edge 12 of the discharge opening 6; and

u=angle between vectors of stresses S and S in case according to FIG. 2, u=.

The yarn tension at the discharge from the spinning chamber 1, the so-called spinning tension S is approximately given by the following equation:

In this equation C=a constant depending on the mass of yarn 5 for a unit of length, the increase in tension due to the bending of the yarn 5 about the edge 12 of the discharge opening 6, and finally other influences;

R=diameter of the collecting surface 2 of the spinning chamber 1; and

n=number of revolutions of the spinning chamber per minute.

In dependence on the coefficient y a number of curves z=y-ln-f(x) are shown in FIG. 3 which are diagrammatically plotted for the coefiicients y y y". To these curves corresponds a system of curves for the identical coeflicients y y" y"' represented in FIG. 4 wherein each of the curves represents the development of the axial stress S in yarn 5 in the spinning chamber 1 and in these curves S is the stress at the discharge opening 6 and S is the stress at the withdrawal point 4 of the fibrous material from the collecting surface 2. This clearly confirms that stress S is a function of S and the coefficient y, that is s cry From the diagram of FIG. 4 showing the development of the axial stress S, it is further evident that the stress S becomes smaller as the value of the coeflicient y de creases. In actual practice that means that it is necessary for S to be smaller than the tensile stress of the fiber strand at the withdrawal point 4 or, still better, smaller than the permissible stress in the strand.

For normal values of spinning stresses S it was experimentally established that this condition can be best obtained if the coefiicient y is maintained within certain limits. It has been found that advantageous results are obtained when the range of y is maintained between 2010* to 80-10. This range insures that the magnitude of the stress S at the withdrawal point 4 amounts approximately to S 0.00s 0.035 s,

The experiments by means of which the aforementioned range of the coeflicient y was established were carried out by taking, by high speed photography, pictures of the yarn curve in the spinning chamber, by means of which a certain course of the function z(x) has been confirmed. At the same time the angular movement of the yarn and the revolutions of the spinning chamber, which determine the velocities v, and v have been stroboscopically measured. Under these accurately determined conditions spinning tests have then been carried out and breakage rates for the yarn in the spinning chamber have been compared. From the dependence of the breakage rate on the coefiicient y an optimum range for this coefiicient y for a minimum breakage rate has been ascertained.

From the above equations it will be evident that in order to maintain the stress S at the withdrawal point smaller than the permissible stress in the fiber strand to avoid breakage thereof the yarn has to be withdrawn at such a speed so as to maintain the sense of the angular velocity of the relative displacement of the point of withdrawal of the yarn from the collecting surface relative to said surface coincident with the sense of angular velocity of the spinning chamber. It is further evident that in order to obtain best results the coefiicient a should be maintained within a range of y=20'10- to 280-10- By way of examples some suitable chosen values for the coefficient y as well as some unsuitable values for this coefficient are given below.

Suitable chosen values:

lowing magnitudes of the reltaive velocity v, and of the absolute velocity v of the withdrawal point 4:

v,. =44 meters/min; v =920O meters/min for y v =40 meters/min.; v =5400 meters/min for y On the other hand values for the coefiicient which have been proven as unsuitable, resulting in stress S exceeding the permissible stress, are for instance y =200-10- and y =260-10 to which correspond for instance the following lowing combination of relative and absolute velocities of the withdrawal point 4:

v =40 meters/min; v =2000 meters/min for y v =52 meters/min; v =2000 meters/min for 3 It will be understood that each of the elements described above, or two or more together, may also find a useful improvement in other types of method of spinning yarn from a strand of fibers in a spinning chamber differing from the types described above.

While the invention has been illustrated and described as embodied in a method of spinning yarn from a strand of fibers in a spinning chamber, it is not intended to be limited to the details shown, since various modifications and structural changes may be made Without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of spinning yarn from a strand of fibers in a spinning chamber rotatable about an axis and having a smooth collecting surface constituted by a surface of revolution having an axis coinciding with the axis of the spinning chamber, comprising the steps of frictionally twisting a fiber strand deposited on said collecting surface into a yarn and withdrawing said yarn from said collecting surface substantially in a stationary plane normal to the axis of rotation of the spinning chamber and passing through the axis of the strand so that the fiber strand is frictionally twisted symmetrically with respect to its own axis; and rotating said spinning chamber about its axis and simultaneously withdrawing the yarn from said collecting surface at correlated speeds so as to maintain the sense of the angular velocity of the relative displacement of the point of withdrawal of the yarn from said collecting surface relative to said surface coincident with the sense of angular velocity of the spinning chamher.

2. A method as defined in claim 1, and maintaining the correlation between said speeds in such a manner that the velocity of the withdrawal point of the yarn from the collecting surface relative to the velocity of the collecting surface divided by the absolute velocity of said withdrawal point is maintained within the range of 20- 10- to 18()-10 and maintaining thereby the stress S on the fiber strand at the withdrawal point from the collecting surface with respect to the stress S at the discharge from the spinning chamber within the limits s,=0.0s s to 0.035 s References Cited UNITED STATES PATENTS 3,163,976 1/1965 Juillard 57-58.89 3,210,923 10/1965 Schlosser 57--l56 XR 3,324,642 6/1967 Meimberg et al. 5758.93 XR FOREIGN PATENTS 1,031,150 5/1966 Great Britain.

FRANK J. COHEN, Primary Examiner.

W. H. SCHROEDER, Assistant Examiner. 

